Re: [HACKERS] [PATCH] WIP Add ALWAYS DEFERRED option forconstraints

On 10/03/2017 10:10 PM, Andreas Joseph Krogh wrote:
> While we're in deferrable constraints land...;
> I even more often need deferrable /conditional /unique-indexes.
> In PG you now may have:
>
> ALTER TABLE email_folder ADD CONSTRAINT some_uk UNIQUE (owner_id, folder_type, name) DEFERRABLE INITIALLY DEFERRED;
>
> 
> But this isn't supported:
>
> CREATE UNIQUE INDEX some_uk ON email_folder(owner_id, folder_type, name) WHERE parent_id IS NULL DEFERRABLE INITIALLY DEFERRED;
>
> Are there any plans to support this?

I don't want to hijack the thread, but you can do that with exclusion
constraints.